import java.util.HashSet;
import java.util.Locale;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 25228
 * Date: 2024-10-10
 * Time: 8:21
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        QuadraticSolver quadraticSolver = new QuadraticSolver();
        CostEstimator costEstimator = new CostEstimator();
        Pentagon pentagon=new Pentagon();
        Robot robot=new Robot();
        String s;
        s=scanner.nextLine();
    }
}

class QuadraticSolver {
    public void solve(double a, double b, double c) {
        if (a == 0) {
            if (b == 0) {
                System.out.println("invalid");
            } else {
                double x = -c / b;
                System.out.println(1); // 一个解
                String s = String.format("%6f", x);
                System.out.println(s);
            }
        } else {
            double discriminant = b * b - 4 * a * c;

            if (discriminant < 0) {
                System.out.println("invalid");
            } else if (discriminant == 0) {
                System.out.println(1);
                double x1 = -b / (2 * a);
                String s = String.format("%6f", x1);
                System.out.println(s);
            } else {
                System.out.println(2);
                double x1 = (-b + Math.sqrt(discriminant)) / (2 * a);
                double x2 = (-b - Math.sqrt(discriminant)) / (2 * a);
                if (x1 > x2) {
                    double temp = x1;
                    x1 = x2;
                    x2 = temp;
                }
                String s = String.format("%6f %6f", x1, x2);
                System.out.println(s);
            }
        }
    }
}

class CostEstimator {
    public double estimate(double weight) {
        if (weight > 20 || weight < 0) {
            return -1;
        }
        if (weight <= 1) {
            return 3.5;
        } else if (weight <= 3) {
            return 5.5;
        } else if (weight <= 10) {
            return 8.5;
        } else {
            return 10.5;
        }
    }
}

class Pentagon {
    double getArea(double r) {
        return (5 * Math.pow(2 * r * Math.sin(Math.PI / 5), 2)) / (4 * Math.tan(Math.PI / 5));
    }
}

class Robot {
    public void sayHello(String name) {
        System.out.println("Hello! My name is " + name + "!");
    }

    public void dance() {
        System.out.println("I will start dancing now!");
    }

    public void sayGoodbye() {
        System.out.println("Bye!");
    }
}

class Palindrome {
    public static boolean check(String s) {
        String s2 = s.toLowerCase();
        StringBuilder s3 = new StringBuilder();
        for (int i = 0; i < s2.length(); i++) {
            if (Character.isLetterOrDigit(s2.charAt(i))) {
                s3.append(s2.charAt(i));
            }
        }
        int i = 0;
        int j = s3.length() - 1;
        while (i < j) {
            if (s3.charAt(i) != s3.charAt(j)) {
                return false;
            } else {
                i++;
                j--;
            }
        }
        return true;
    }
}

class MorseCode {
    public static int translate(String words) {
        HashSet<String> set = new HashSet<>();
        StringBuilder stringBuilder = new StringBuilder();
        for (char c : words.toCharArray()) {
            if (c != ' ') {
                stringBuilder.append(c);
            } else {
                // 当遇到空格时，将当前单词转换为摩尔斯电码并添加到set中
                String morseCode = convertToMorse(stringBuilder.toString());
                set.add(morseCode);
                stringBuilder.setLength(0);
            }
        }
        //添加最后一个单词
        String morseCode = convertToMorse(stringBuilder.toString());
        set.add(morseCode);
        return set.size();
    }

    public static String convertToMorse(String words) {
        String[] strings = new String[]{".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."};
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < words.length(); i++) {
            stringBuilder.append(strings[words.charAt(i) - 'a']);
        }
        return stringBuilder.toString();
    }
}
